Environmental Health Perspectives • volume 120 | number 5 | May 2012
Arsenic (As) is an established carcinogen
based on studies of populations consuming
contaminated drinking water (Smith et al.
2002). Recently, attention has focused on As
exposure from food, in particular fruit juices
(Rock 2012) and rice (Stone 2008). Rice
may contain As in total concentrations up to
100–400 ng/g, including both inorganic As
(Asi) and the organic species dimethyl arsenate
(DMA) (Williams et al. 2005), with much
lower concentrations (relative to DMA) of
mono methyl arsenate (MMA) also occasion-
ally detected. Total As (Astotal) in rice and
relative proportions of DMA and Asi differ
both geographically (Meharg et al. 2009) and
as a function of genetic and environmental
controls (Norton et al. 2009).
As i is more toxic than DMA or MMA (Le
et al. 2000), and food regulatory limits, where
they exist, are based on Asi. Infants fed rice
cereal at least once daily may exceed the daily
As exposure limit of 0.17 µg/kg body weight
per day based on drinking water standards
(Meharg et al. 2008b). Rice products such
as cereals and crackers (Sun et al. 2009) and
rice drinks (Meharg et al. 2008a) are poten-
tially significant dietary sources of As. Infants
and young children are especially vulnerable
because their dietary As exposure per kilogram
of body weight is 2–3 times higher than that
of adults [European Food Safety Authority
DMA is a metabolite of Asi. Although
considered less toxic than Asi, its toxicologi-
cal potential has not been studied extensively.
The presence of DMA in rice is likely due
to natural soil microbial processes; however,
DMA was used as a pesticide before being
banned by the U.S. Environmental Protection
Agency (EPA) in 2009 (U.S. EPA 2009).
Organic food consumers may therefore object
to its presence in organic foods even in the
absence of direct evidence of human health
effects of DMA.
In the United States, organic brown rice
syrup (OBRS) is used as a sweetener as a
healthier alternative to high-fructose corn
syrup in products aimed at the “organic
foods” market. Added sugar is often the main
ingredient in infant and toddler formula,
and the addition of sucrose to a main-brand
organic formula was the feature of a popular
press article in relation to possible childhood
obesity (Moskin 2008). Many products—
including some baby milk formulas, cereal
bars, and high-energy performance products
for athletes—list OBRS as the major
ingredient. Brown rice is usually higher in
both Astotal and Asi than white rice because
Asi is localized to the aleurone layer, which is
removed when rice is polished, whereas DMA
passes into the grain (Carey et al. 2011; Sun
et al. 2008). Ranges of As concentration in
rice products, including OBRS, are similar
to As concentrations in brown rice (Signes-
Pastor et al. 2009).
We posit that consumers of organic food
products are generally attempting to make
educated eating choices and that this consumer
group would be particularly interested to know
if, and to what extent, OBRS introduces Asi,
DMA, and MMA into these products. We
therefore measured Astotal and As speciation
in three commercially available brown rice
syrups, 15 infant formulas without OBRS,
2 toddler formulas with OBRS, 29 cereal bars
(13 with OBRS), and three flavors of a high-
energy performance product.
Materials and Methods
We purchased three commercial OBRSs from
local or online stores. For one syrup, two bot-
tles of the same product (from different lots)
were tested. Fifteen infant formulas and two
toddler formulas (initially purchased as part
of a parallel study on As content of formulas
and infant foods), as well as 29 cereal bars
and three energy shot blocks were all pur-
chased from local stores in the Hanover, New
Sample preparation. All samples were
analyzed for Astotal, and selected samples
were extracted for As species. For formulas,
Astotal was determined after closed vessel
micro wave digestion (MARSXpress; CEM
Corp., Matthews, NC) with Optima HNO3.
Approximately 0.25 g formula was digested in
2 mL 50% HNO3 (nitric acid). The samples
Address correspondence to B. Jackson, Trace Element
Analysis Core, Dartmouth College, Hanover, NH,
03755 USA. Telephone: (603) 646-1272. Fax: (603)
646-3922. E-mail: BPJ@dartmouth.edu
We thank L. Webb for assistance with market-
basket research and J. Chen for assistance in the
This work was supported by grants P20 ES018175
and P42 ES007373 from the National Institute
of Environmental Health Sciences (NIEHS) and
RD-83459901-0 from the U.S. Environmental
Protection Agency (EPA).
The NIEHS and U.S. EPA were not involved in
the design and conduct of the study or collection,
management, analysis, and interpretation of the data.
The contents of this manuscript are solely the respon-
sibility of the authors and do not necessarily repre-
sent the official views of the NIEHS or U.S. EPA.
Further, the U.S. EPA does not endorse the purchase
of any commercial products or services mentioned in
The authors declare they have no actual or potential
competing financial interests.
Received 13 October 2011; accepted 13 February
Arsenic, Organic Foods, and Brown Rice Syrup
Brian P. Jackson,1 Vivien F. Taylor,1 Margaret R. Karagas,2 Tracy Punshon,3 and Kathryn L. Cottingham3
1Trace Element Analysis Core Laboratory, Department of Earth Sciences, Dartmouth College, Hanover, New Hampshire, USA;
2Department of Community and Family Medicine, Section of Biostatistics and Epidemiology, Dartmouth Medical School, Lebanon,
New Hampshire, USA; 3Department of Biological Sciences, Dartmouth College, Hanover, New Hampshire, USA
Background: Rice can be a major source of inorganic arsenic (Asi) for many sub populations. Rice
products are also used as ingredients in prepared foods, some of which may not be obviously rice based.
Organic brown rice syrup (OBRS) is used as a sweetener in organic food products as an alternative to
high-fructose corn syrup. We hypothesized that OBRS introduces As into these products.
oBjective: We determined the concentration and speciation of As in commercially available brown
rice syrups and in products containing OBRS, including toddler formula, cereal/energy bars, and
high-energy foods used by endurance athletes.
Methods: We used inductively coupled plasma mass spectrometry (ICP-MS) and ion
chromatography coupled to ICP-MS to determine total As (Astotal) concentrations and As speciation
in products purchased via the Internet or in stores in the Hanover, New Hampshire, area.
discussion: We found that OBRS can contain high concentrations of Asi and dimethyl arsenate
(DMA). An “organic” toddler milk formula containing OBRS as the primary ingredient had Astotal
concentrations up to six times the U.S. Environmental Protection Agency safe drinking water limit.
Cereal bars and high-energy foods containing OBRS also had higher As concentrations than equiva-
lent products that did not contain OBRS. Asi was the main As species in most food products tested
in this study.
conclusions: There are currently no U.S. regulations applicable to As in food, but our findings
suggest that the OBRS products we evaluated may introduce significant concentrations of Asi into an
individual’s diet. Thus, we conclude that there is an urgent need for regulatory limits on As in food.
key words: arsenic, baby formula, brown rice syrup, cereal bars, energy bars, organic foods,
speciation. Environ Health Perspect 120:623–626 (2012). http://dx.doi.org/10.1289/ehp.1104619
[Online 16 February 2012]
Jackson et al.
volume 120 | number 5 | May 2012 • Environmental Health Perspectives
were heated at 180°C for 10 min, allowed
to cool, and then diluted to 10–25 mL with
deionized water. Cereal bars and energy blocks
were homogenized using a ceramic knife and
were not dried before digestion. A sub sample
was digested in 2–3 mL Optima HNO3 and
heated at 95°C for 30 min. The digested sample
was diluted with deionized water to 25–50 mL.
This digested sample was diluted a further 10×
before analysis to reduce the acid concentration
in the sample to < 5%. All digestions and
dilutions were recorded gravimetrically.
Samples were extracted for As speciation using
1% HNO3 and open-vessel heating in a micro-
wave digestion unit following a heating profile
of 55°C for 5 min, 75°C for 5 min, and 95°C
for 20 min (Foster et al. 2007; Huang et al.
2010). An aliquot of the extracted sample was
then centrifuged at 13,300 rpm for 30 min;
an aliquot of that supernatant was further spin
filtered at 10 kDa.
Astotal and As speciation. Astotal was
determined by inductively coupled plasma
mass spectrometry (ICP-MS; model 7700x;
Agilent, Santa Clara, CA) using helium as a
collision gas at a flow rate of 4.5 mL/min.
Samples were analyzed by either external cali-
bration or the method of standard additions.
As speciation of the 1% HNO3 extracts was
determined by ion chromatography coupled to
ICP-MS using a Hamilton PRP X100 anion
exchange column (Hamilton Company, Reno,
NV) and a 20 mM ammonium phosphate
eluant at pH 8. Formulas were evaluated in
triplicate, and 5% duplicate and duplicate
spikes were performed for the cereal bars and
We used NIST Standard Reference
Material (SRM) 1568a rice flour (National
Institute of Standards and Technology,
Gaithersburg, MD) as a quality control mate-
rial for both Astotal measurements and As
speciation. Although As species are not cer-
tified for SRM 1568a, reproducible consen-
sus values have been demon strated in many
studies (Meharg and Raab 2009; Raab et al.
2009; Williams et al. 2005). We determined
Astotal in SRM 1568a to be 279 ± 31 ng/g
(mean ± 1 SD; n = 6); the certified value is
290 ± 30 ng/g. For As speciation (n = 5),
we determined DMA to be 186 ± 21 ng/g,
MMA to be 9.4 ± 3.7 ng/g, and Asi to be
101 ± 15 ng/g, which are in the range reported
by other studies.
Data analyses. Given our calculated
values for As speciation in the formulas, we
estimated As concentrations (micrograms per
liter) of reconstituted formulas assuming that
one scoop of powdered formula weighs 8.75 g
and that one scoop of formula is added to
60 mL As-free water to make 2 fluid ounces
of formula. We then estimated daily intake of
As species for a baby weighing 6 kg and 9 kg,
assuming consumption of six 4-ounce bottles
of milk formula each day, and compared this
with “safe” levels estimated for consumption
of drinking water containing Asi at the
U.S. EPA and World Health Organization
(WHO) maximum contaminant limit of
10 µg/L (Meharg et al. 2008b).
Results and Discussion
Rice syrups. Astotal concentrations in three rice
syrups (and from two lots of one of the syrups)
ranged from 80 to 400 ng/g (Table 1). Asi was
80–90% of Astotal for two of the three syrups;
for the third syrup, only 50% of Astotal was Asi.
However, because this syrup was much higher
in Astotal, it also had the highest Asi concentra-
tion of the syrups. All syrups had detectable
MMA, ranging from 3 to 4% of Astotal, but
the major organic As species for each syrup
was DMA. Our results are similar to those of
Signes-Pastor et al. (2009) who reported dry
weight Astotal concentrations of 80, 100, 120,
and 330 ng/g in four rice syrups, with 71% Asi
and 85% extraction efficiency in the highest
As syrup. Moreover, given these authors’ esti-
mate of 15% moisture content for the syrups,
we estimate that the actual contribution to As
concentration in food products that include
OBRS as the dried product—such as toddler
formulas—would be approximately 1.15 times
the concentration listed in Table 1.
Baby formulas. We analyzed 17 different
formulas. Average Astotal concentrations in the
15 infant formulas that did not contain OBRS
were relatively low, in the range of 2–12 ng/g
(Jackson et al. 2012). Those results were consis-
tent with two other studies of As in infant for-
mula (Ljung et al. 2011; Vela and Heitkemper
2004). However, the As concentrations in the
two toddler formulas that listed OBRS as the
primary ingredient (one dairy-based and one
soy-based) were > 20 times the As concen-
trations in infant formulas that did not con-
tain OBRS (Figure 1A). The proportion of
Asi varied among products and among lots
of the soy-based formula, but the concentra-
tion of Asi in the reconstituted formulas with
OBRS was either just below (dairy, 8–9 µg/L)
or 1.5–2.5 times above (soy) the current U.S.
drinking water standard (10 µg/L). In addition,
the OBRS formulas contained 19–40 µg/L
DMA and trace levels of MMA. Expressed as
daily As intake per kilogram of body weight,
the exposure of infants and toddlers drinking
OBRS-containing milk products is even more
apparent (Figure 1B). Using web-based search
engines, we found only these two toddler
formulas that used OBRS, so the number of
infants using this formula is presumably a very
low percentage of U.S. formula-fed infants.
Infants, in a phase of rapid development,
are especially vulnerable to contaminants, and
emerging data suggest that As exposure early
in life may pose risks not only during child-
hood but also in adult life (Vahter 2009).
This suggests that we need to pay particular
attention to the potential for As exposure dur-
ing infancy. The standards and guidelines for
daily intake of As are currently a matter of
debate (Meharg and Raab 2009; Meharg et al.
2008b). The WHO established a provisional
maximum tolerable daily intake (PMTDI)
Table 1. As concentrations and As speciation for three OBRSs.
(mean ± 1 SD)]
78 ± 6
94 ± 8
136 ± 3
406 ± 6
A, lot 1
A, lot 2
Analyses were performed in triplicate.
Sum of As species (ng/g)
Figure 1. Asi and DMA concentrations in milk formulas with and without OBRS. (A) Concentrations of Asi
and DMA in prepared formula in reconstituted milk formulas relative to the current WHO and U.S. EPA
drinking water standard of 10 µg/L (horizontal line). (B) Daily As intake for a 9‑kg baby drinking six 4‑ounce
bottles of milk formula reconstituted with As‑free water relative to a 60‑kg adult drinking 2 L tap water at
the safe drinking water limit (horizontal line). Data are mean ± SD. The No OBRS bars are calculated from
15 different main‑brand milk formulas (Jackson et al. 2012); the OBRS bars are based on triplicate analysis
from one lot (a or b) of each type.
No OBRS Dairy (a) Dairy (b)Soy (a)Soy (b)Dairy (a) Dairy (b)Soy (a)Soy (b)
As (µg/kg body mass/day)
Arsenic, organic foods, and brown rice syrup
Environmental Health Perspectives • volume 120 | number 5 | May 2012
guideline of 2.1 µg/kg/day in 1983 (Food
and Agriculture Organization of the United
Nations/WHO 1983). For an infant weigh-
ing either 6 or 9 kg, both of the OBRS for-
mulas would be above this value based on
Astotal; for a 6-kg infant, the soy formulas
would be above the guideline based only on
Asi. It should be noted that the WHO 1983
PMTDI is based on a safe drinking water
limit of 50 µg/L rather than the current limit
of 10 µg/L [European Food Safety Authority
(EFSA) 2009; Meharg and Raab 2009].
Currently, only China has a limit for As in
food: an Asi limit of 150 ng/g for rice (Zhu
et al. 2008). Although the OBRS toddler for-
mulas would not exceed this limit on average,
Astotal and Asi concentrations of these OBRS
formulas are cause for concern.
Cereal and energy bars. OBRS is also a
popular sweetener for many cereal/energy bars
and high-energy athletic performance products.
Our web- and store-based market survey of
100 bars indicated that about 50% contain
either OBRS (31%), other rice products (5%),
or both (14%). We tested 29 bars and three
types (flavors) of an energy product obtained
from a local supermarket. The results for the
cereal/energy bars are shown in Table 2. All
of the bars had detectable Astotal with a range
of 8–128 ng/g. The 7 bars that did not list any
rice product among the top five ingredients
were among the 8 lowest As-containing
bars we tested. The remaining bars listed at
least one of four rice products (OBRS, rice
flour, rice grain, and rice flakes) in the first
five ingredients and had Astotal concentrations
ranging from 23 to 128 ng/g.
We analyzed As speciation in 12 of the
rice-containing bars. Of the 12 bars, 11 con-
tained Asi concentrations > 50%, with an aver-
age of 70% Asi. All organic As was DMA. The
percent recovery (sum of As species as a per-
centage of Astotal) ranged from 67% to 124%;
however, some of this variability is because the
bars were not dried before analysis and were
analyzed “as is,” with limited homogenization
using a ceramic-bladed knife. The amount of
Asi ingested when eating one of these bars is
a function of the As concentration of the bar
and the size (weight) of the bar. The bars we
analyzed ranged in weight from 28 to 68 g; at
the upper limit of bar weight and Asi content,
an individual bar contained up to 4 µg Asi.
For example, bar 27 weighed 45 g and con-
tained 101 ng/g Astotal and 79% Asi, equating
to an Asi content of 3.6 µg.
Energy shot blocks. We also analyzed As
concentration and speciation in three high-
energy products for endurance athletes
known as “energy shot blocks," each of which
contained OBRS. Although an educated
consumer might be aware of the potential for
rice to contain As (and therefore know that
products containing rice ingredients might
also contain As), the energy shot blocks are
gel-like blocks, so it would not be immediately
apparent to the consumer that these too are
The As concentration in one of the energy
shot blocks containing OBRS was 84 ± 3 ng/g
Astotal (n = 3), which was 100% Asi. The
other two energy shot blocks were very simi-
lar to one another in Astotal concentrations
(171 ± 3.6 ng/g, mean ± SD; n = 6) and spe-
ciation (53% Asi). No MMA was detected in
the energy shot blocks. All three flavors con-
tained 2.5–2.7 µg Asi per 30-g serving. The
manufacturer recommends consuming up to
two servings (60 g) per hour during exercise,
so an endurance athlete consuming four serv-
ings during a 2-hr workout would consume
approximately 10 µg Asi per day, equal to the
Asi intake resulting from consumption of 1 L
of water at the current U.S. EPA and WHO
limit of 10 µg/L. Athletes consuming the two
flavors containing 171 ng/g Astotal would also
consume 2.5 µg DMA per 30-g serving.
Food is a major pathway of exposure to As
for most individuals (EFSA 2009). Rice and
rice products can contribute to an individual’s
Asi exposure (Meharg et al. 2008a, 2008b;
Williams et al. 2005). There is a growing
Table 2. As concentrations and speciation in 29 cereal bars, with information about their rice‑based
Sample IDAstotal (ng/g)Percent Asi
body of information about As concentration
and speciation in rice in the peer-reviewed
literature and thus in the public domain, but
much less information is available on rice-
based food products. Rice products are used
in a variety of foods, including gluten-free
products and, as we show here, in products
where OBRS is used as an alternative to high-
fructose corn syrup. The formulas containing
OBRS—which could be the sole sustenance
for an individual over a critical period of
develop ment—can result in consumption of
milk with As concentrations much higher
than the drinking water standard, yet there
are no U.S. regulations to deal with this
particular scenario. Similarly, endurance
athletes who consume 4 servings of OBRS-
containing energy shot blocks (manufacturer-
recommended maximum for 2 hr of physical
activity) may be exposed to as much as 10 µg
Asi and 20 µg Astotal in a single day. Moreover,
the major As species in the overwhelming
majority of food products we have tested is
the more toxic Asi, a finding that, although
noted in other studies (Sun et al. 2009), is
particularly troubling given the non threshold
relation ships between cancer risk and exposure
to Asi (National Research Council 2001).
There are currently no U.S. regulations
applicable to As in food, but our findings
—, sample was not speciated. Check marks indicate the presence of a rice‑based ingredient (flakes, grain, flour, or
brown rice syrup), and numbers in parentheses indicate the order of that ingredient in the ingredients list (only the first
five listed ingredients were considered).
Jackson et al.
volume 120 | number 5 | May 2012 • Environmental Health Perspectives
suggest that the OBRS-containing products
we evaluated may introduce significant con-
centrations of Asi into an individual’s diet.
Thus, we conclude that there is an urgent
need for regulatory limits on As in food.
In the manuscript originally published
online, the two OBRS formulas were incor-
rectly identified as infant formula when
they are in fact toddler formula. Toddler
formula is not intended for infants under
1 year of age unless specified by a health
care professional. Figure 1B has been recal-
culated to reflect a 9-kg body weight, the
median weight for a 12-month-old baby.
Because Figure 1B was recalculated using
an updated version of the speciation data,
Figure 1A has also been updated for consis-
tency. The text has been modified to reflect
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